Artificial turf grass with natural appearance

ABSTRACT

Disclosed herein is a turf filament comprising from 50 to 99.5 weight percent of abase polymer selected from polyolefins, polyamides, polyesters and combinations thereof, from 0.1 to 20 weight percent of polymer particles having a core and a shell structure where the core comprises a first polymeric material having a first refractive index and the shell comprises a second polymeric material having a second refractive index that is different from the first refractive index, from 0.5 to 30 weight percent of a compatibilizer and from 0 to 10 weight percent of a colorant based on total weight of the filaments. Also disclosed is a synthetic turf comprising such filaments. These filaments provide a turf with a natural appearance.

CROSS REFERENCE TO RELATED APPLICATIONS

This application claims the benefit of European Application No. 19382003.2, filed on Jan. 3, 2019, which is incorporated herein by reference in its entirety

FIELD OF THE INVENTION

The field of this invention is fibers for use in artificial turf and artificial turf having such fibers.

BACKGROUND

Artificial turf is often used to provide ground coverings for sports facilities, such as football or soccer fields, and sometimes for decorative use. A common structure for this artificial turf, particularly for sports fields, includes a sheet-like substrate with a plurality of filiform formations or fibers (i.e., synthetic grass blades or turf yarn or turf filaments) extending from the substrate for simulating the grassy sward of natural turf and a particulate filling material, or infill, dispersed between the filiform formations so as to keep the filiform formations themselves in a substantially upright condition.

The synthetic grass blades are typically made of one or more polymers such as polypropylene, polyethylene, polyesters, and polyamides which may include additive such as IR reflectants, UV stabilizers, fire-retardants, matting agents, luminescent compounds, or fillers. (See e.g., WO2017/211981). EP 3088575 discloses method of manufacture of artificial turf comprising stabilizing polymer which is a polyaramid fiber surrounded by a compatibilizer in a bulk polymer. While use of such polymers is helpful for cost and durability it can lead to an appearance that is not looks synthetic. Having an appearance resembling as closely as possible natural grass is an increasingly important feature for synthetic turf surfaces. Especially for landscaping and residential applications, there is a clear trend in the industry towards a more natural look for the turf.

One approach to provide the surface with more natural appearance is to tuft bundles with strands of 2 or 3 different colors or develop new fiber geometry designs. See e.g. WO2017/211981, WO2015/175786, US 2014/0193593. An alternative strategy is to create melt fracture during the yarn extrusion in order to generate a rougher surface which can reduce the glossy appearance (often related to “plastic” or “synthetic” perception). See e.g. WO2012/164059. However, melt fracture is typically achieved at the expense of draw ratio flexibility or even durability compromise. Despite the many efforts to make artificial turf look more natural, there is still a need for further improvement.

Thus, a need exists for artificial turf having a more natural appearance without a significant decrease in durability or performance of the turf.

SUMMARY OF THE INVENTION

Disclosed herein is a simulated grass structure comprising a substrate having a plurality of turf filaments (also referred to as turf yarn or filiforms) extending from the substrate wherein the turf filaments comprise from 50 to 99.5 weight percent of a base polymer, from 0.1 to 20 weight percent of polymer particles having a core and a shell structure where the core comprises a first polymeric material having a first refractive index and the shell comprises a second polymeric material having a second refractive index that is different from the first refractive index, from 0.5 to 30 weight percent of a compatibilizer, and from 0 to 10 weight percent of a colorant based on total weight of the filaments. The base polymer can comprise a polyolefin.

Also disclosed herein are filaments comprising from 50 to 99.5 weight percent of a base polymer which comprises a polyolefin, from 0.1 to 20 weight percent of polymer particles having a core shell structure where the core comprises a first polymeric material having a first refractive index and the shell comprises a second polymeric material having a second refractive index that is different from the first refractive index, from 0.5 to 30 weight percent of a compatibilizer, and from 0 to 10 weight percent of a colorant based on total weight of the filaments.

The filaments of the above description and the turf grass made with them have a more natural (e.g. grass like) appearance than do filaments made without the acrylic particles. Also, the compatibilizer can enable the filaments to maintain the mechanical strength of the base polymer as compared to filaments that have only the base polymer and the acrylic polymer particles. Finally, in the acrylic polymeric particles in addition to improving the appearance of the yarn can also improve the UV resistance of the yarn.

DETAILED DESCRIPTION OF THE INVENTION

Disclosed herein are artificial turf having turf grass blades or yarn of a specific composition.

The Artificial Turf

The artificial turf can be of any conventional structure of such turf.

For example, the artificial turf can include a substrate to which synthetic grass fibers, (also referred to herein as turf filaments, turf yarn, or filiforms) are attached. The substrate may be a sheet or film like material. It can for example a thermoplastic material. It may be woven or non-woven or a solid film or sheet. The filiforms are elongated objects, or fibers or blades attached to the substrate and protruding upward from the substrate. Synthetic grass fibers can be synthetic extruded fibers (monofilaments) or (slit-film) tapes. The fibers can be arranged in bundles, preferably in bundles of monofilaments. For example, one bundle may contain 4 to 20 fibers. The synthetic grass fibers can have a cross-section selected from, but not limited to, a rectangular, a diamond-shape, a round, an elliptical, a multilobal (Y, X), a C-shaped, a V-shaped, a W-shaped, a S-shaped or a Ω-shaped cross-section, and have dimensions of e.g. 50-500 micrometers thickness and 0.5-5.0 mm width. The synthetic grass fibers may further comprise a backbone, and/or a micro-textured surface to resemble grass blade nerves to further improve the resemblance to natural grass blades. The synthetic grass fibers are typically in a green color e.g. a uni-color or a mixed shade of green and other colors. The synthetic grass fibers can be tufted or woven through the backing. For example, the fibers can be tufted through the backing substrate. The synthetic grass fibers can be formed in loop piles or cut piles. The filiforms can extend from the substrate for a length of from 20 or from 30 to 60 or to 50 mm. A backsheet on the backside of the substrate opposite the side from which the filiforms extend can also be used to help hold the fibers, yarn or filiforms in place.

The artificial turf can also include small particles or granules, often called infill. The infill can be found on the substrate and between the fibers to help the fibers remain upright. The infill can have sizes of at least 1 mm up to about 5, up to 4, or up to 3 mm. The infill extends from the surface of the substrate for at least 5 or at least 10 mm to 30 or to 20 mm to support the filiform. The infill can be recycled rubber, elastomers, thermoplastics or combinations thereof.

Turf Filament Composition and Structure

The turf filaments disclosed herein are made from a composition comprising a base polymer, acrylic polymeric particles, a compatibilizer, and optionally a colorant. The composition can further comprise one or more of the following additional optional ingredients: infrared reflectants, UV stabilizers, anti-oxidants, fire-retardants luminescent compounds (phosphorescent or fluorescent compounds), fillers (e.g. chalk, talc). If any of these optional components are used they are preferably used in amounts of no more than 10 or no more than 5 weight percent based on total weight of the filament. The total amount (i.e. combined amount) of the optional components, if any is no more than 10 weight percent for all the additives combined based on total weight of the filament.

Base Polymer

The base polymer is a polymer which can be formed into fibers or filaments. It can comprise a polyolefin, such as polypropylene (PP) or polyethylene (PE); a polyester, such as polyethylene terephthalate (PET); or a polyamide (PA) or combinations thereof. For example, the base polymer can be a polyethylene (PE), such as high density polyethylene (HDPE), low density polyethylene (LDPE) or linear low density polyethylene (LLDPE); or a polypropylene. LLDPE shows good softness and resiliency. The base polymer can be a linear low density polyethylene resin with a density from 0.905 to 0.960 g/cc, preferably from 0.915 to 0.922 g/cc; and melt index measured at 190° C. from 0.5 to 10 g/10 min, preferably from 1.5 to 4.5 g/10 min. Commercial examples are DOWLEX™ 2107GC, DOWLEX™ 2607GC or ELITE™ 5230GC all from The Dow Chemical Company. An LLDPE can be blended with one of the other base polymer materials. For example, the base polymer can comprise LLDPE and one or more of HDPE, LDPE, PP, PET, or PA. The amount of such one or more additional polymers can be no more than 30, no more than 20, or no more than 10 weight % based on total weight of the base polymer. Thus, for example, the base polymer can comprise 70 to 100 weight percent LLDPE, and 0 to 30 weight percent in total of one or more of such additional polymers. The filaments can comprise the base polymer in amounts of at least 50, at least 60, at least 70, at least 75, at least 80, or at least 85 weight percent based on total weight of the filament. The filaments can comprise the base polymer in amounts of no more than 99.8, no more than 99.5, no more than 99, no more than 95, or no more than 90 weight percent based on total weight of the filament.

Core/Shell Polymeric Particle

The core/shell polymeric particles are present in amounts of at least 0.1, at least 0.5, or at least 1 weight percent based on total weight of the filament. The core/shell polymeric particles are present in amounts of no more than 20, no more than 15, no more than 10, no more than 7, or no more than 5 weight percent based on total weight of the filament. The particles can have an average particle size of at least 0.5 or at least 1 micron and no more than 15, no more than 12, or no more than 10 microns. Particle size can be determined by using normally methods, e.g. use of a particle sizer such as Model BI-90 from Brookhaven Instrument. Particle size can be measured in powder state. Particle size can show the size of agglomerated core shell particles. Core-shell particles may be purchased with a nominal particle size as specified by the vendor. The core/shell particles can be formed from acrylic monomers such as butyl acrylate, 2-ethylhexyl acrylate and lauryl methacrylate.

The core/shell polymeric particles can be characterized in that polymer in the core has a different refractive index from the refractive index of the polymer in the shell. For example, the refractive index of the polymer in the core can differ from the refractive index of the polymer in the shell by at least 0.02 or at least 0.03. Refractive index can be measured for example using a refractometer and following ASTM D542. The core shell material can be pressed into a thin film by hot press to facilitate this measurement.

The core/shell particles can have an elastomeric core with a thermoplastic shell. For example, the particle can have a rubber particle core formed by a polymer comprising an elastomeric or rubbery polymer as a main ingredient, optionally an intermediate layer formed with a monomer having two or more double bonds and coated on the core layer, and a shell layer formed by a polymer graft polymerized on the core or on an intermediate layer. The shell layer partially or entirely covers the surface of the rubber particle core by graft polymerizing a monomer to the core. At least 30%, at least 40%, at least 50% or at least 60% up to 95, up to 90 up to 85 or up to 80% of the weight of the particle can be the core.

Generally, the polymer constituting the rubber particle core can have a glass transition temperature (Tg) of 0° C. or lower or −30° C. or lower Tg can be determined by DSC measurement or can be calculated for copolymers using the Fox equation [Bulletin of the American Physical Society 1, 3 Page 123 (1956)] as follows 1 T g=w₁×T g₍₁₎+w₂ T g₍₂₎. For a copolymer, w₁ and w₂ refer to the weight fraction of the two comonomers, and T_(g(1)) and T_(g(2)) refer to the glass transition temperatures of the two corresponding homopolymers in Kelvin. For polymers containing three or more monomers, additional terms are added (w_(n)/T_(g(n)). The T_(g) of a polymer phase can also be calculated by using the appropriate values for the glass transition temperatures of homopolymers, which may be found, for example, in “Polymer Handbook”, edited by J. Brandrup and E. H. Immergut, Interscience Publishers.

The polymer constituting the rubber particle core can be made from an elastomeric material comprising from 50 weight percent to 100 weight percent of at least one member selected from diene monomers (conjugated diene monomers) and (meth)acrylic acid ester monomers and 0 to 50 weight percent of other copolymerizable vinyl monomers, polysiloxane type elastomers or combinations thereof wherein the weight percents are based on total weight of the elastomeric material. The term ‘(meth)acryl’ is defined as acryl and/or methacryl.

The diene monomer (conjugated diene monomer) used in making the elastomeric material can include but is not limited to, for example, butadiene, isoprene and chloroprene. Butadiene can be used. Further, the (meth)acrylic ester monomer can include, for example, butyl acrylate, 2-ethylhexyl acrylate and lauryl methacrylate can be used alone or in combination.

Further, the above-mentioned elastomeric materials of a diene monomer or (meth) acrylate ester monomer can also be a copolymer of a vinyl monomer copolymerizable therewith. The vinyl monomer copolymerizable with the diene monomer or (meth)acrylic ester monomers can include, for example, aromatic vinyl monomers and vinyl cyanate monomers. Examples of aromatic vinyl monomers that can be used include but are not limited to styrene, alpha-methylstyrene, and vinyl naphthalene, while examples of vinyl cyanate monomers that can be used include but are not limited to (meth)acrylonitrile and substituted acrylonitrile. The aromatic vinyl monomers and vinyl cyanate monomers can be used alone or in combination.

The amount of the diene monomer or (meth)acrylic ester monomer used can be in the range of from 50 weight percent to 100 weight percent or from 60 weight percent to 100 weight percent based on the entire weight of the elastomeric material. If the amount of the diene monomer or (meth)acrylic ester monomer to be used for the entire rubber elastomer is less than 50 weight percent, the ability of the polymer particles to toughen a polymer network, such as a cured epoxy matrix, is decreased. The amount of the monomer copolymerizable therewith can be 50 weight percent or less or 40 weight percent or less based on the entire weight of the elastomeric material.

Further, as an ingredient constituting the elastomeric material, a polyfunctional monomer can also be included for controlling the degree of crosslinking. The polyfunctional monomer can include, for example, divinylbenzene, butanediol di(meth)acrylate, triallyl (iso)cyanurate, allyl(meth)acrylic, diallyl itaconate, and diallyl phthalate. The polyfunctional monomer can be used in an amount in the range of from 0 weight percent to 10 weight percent, from 0 weight percent to 3 weight percent, or from 0 weight percent to 0.3 weight percent, based on the entire weight of the elastomeric material. In the case where the amount of the polyfunctional monomer exceeds 10 weight percent, the ability of the polymer particles to toughen a polymer network can be decreased.

Optionally, a chain transfer agent can be used for controlling the molecular weight or the crosslinking density of the polymer constituting the elastomeric material. The chain transfer agent can include, for example, an alkylmercaptan containing from 5 to 20 carbon atoms. The amount of the chain transfer agent in the recipe can be in the range of from 0 weight percent to 5 weight percent, or from 0 weight percent to 3 weight percent based on the entire weight of the elastomeric material. In the case where the amount exceeds 5 weight percent, the amount of the non-crosslinked portion in the rubber particle core increases, which can result in undesired effects on the heat resistance, rigidity, etc. of the composition when it is incorporated into an epoxy resin composition.

A polysiloxane type elastomer can be used in place of the elastomeric material described above as the rubber particle core or in combination therewith. In the case where the polysiloxane type elastomer is used as the rubber particle core, a polysiloxane type elastomer constituted of dialkyl or diaryl substituted silyloxy unit, for example, dimethyl silyloxy, methylphenyl silyloxy, and diphenyl silyloxy can be used. When using such a polysiloxane type elastomer, a crosslinked structure can be introduced by using a polyfunctional alkoxy silane compound or with radial polymerization of silane compound having a vinylic reactive group.

The polymer particles can be configured to have an intermediate layer between an elastic core layer and a shell layer. The intermediate layer is formed by using a monomer (hereinafter, sometimes referred to as a “monomer for intermediate layer formation”) having two or more polymerizable (radical polymerizable) double bonds in a single molecule. Through one of the double bonds, the monomer for intermediate layer formation is graft-polymerized with a polymer forming the elastic core layer to substantially chemically bond the intermediate layer and the shell layer and, at the same time, through the remaining double bond(s), can crosslink the surface of the elastic core layer or can bond to the shell layer. This can improve the grafting efficiency of the shell layer, since many double bonds are arranged in the elastic core layer. The intermediate layer is present in an amount of from 0 or from 0.2 weight percent to 7 weight percent of the polymer particles. The monomer having two or more double bonds and can be selected from the group consisting of (meth)acrylate type polyfunctional monomers, isocyanuric acid derivatives, aromatic vinyl type polyfunctional monomers, and aromatic polycarboxylic acid esters. Radical polymerizable double bonds are more efficient to form a crosslinked layer that covers surface of the elastic core layer. The mass of the monomers forming the intermediate layer equals the mass of the intermediate layer, assuming all monomers added to the formulation participated in the reaction to form the intermediate layer.

The shell layer can be graft polymerized with the polymer constituting the rubber particle core, substantially forming a chemical bond with the polymer constituting the core directly or via the intermediate layer. At least 70 weight percent, at least 80 weight percent, or at least 90 weight percent of the polymer constituting the shell layer can be bonded with the core.

The polymer constituting the shell layer can be a polymer or copolymer obtained by polymerizing or copolymerizing one or more ingredients selected from the group consisting of (meth)acrylic esters, aromatic vinyl compounds, vinyl cyanate compounds, unsaturated acid derivatives, (meth)acrylamide derivatives and maleimide derivatives.

Examples of the (meth)acrylic esters that can be used include, but are not limited to alkyl(meth)acrylate esters such as methyl(meth)acrylate, ethyl(meth)acrylate, butyl(meth)acrylate, and 2-ethylhexyl(meth)acrylate. Examples of the aromatic vinyl compounds include, but are not limited to styrene, a-methylstyrene, alkyl-substituted styrene, and halogen-substituted styrenes such as bromo styrene or chloro styrene.

Examples of vinyl cyanate compounds include, but are not limited to (meth)acrylonitrile and substituted acrylonitrile. Examples of the monomers containing the reactive functional group include, but are not limited to 2-hydroxylethyl (meth)acrylate, 2-aminoethyl(meth)acrylate, glycidyl(meth)acrylate, and (meth)acrylate esters having a reactive side chain. Examples of the vinyl ether containing a reactive group include but are not limited to glycidyl vinyl ether and allyl vinyl ether. Examples of the unsaturated carboxylic acid derivatives include but are not limited to (meth)acrylic acid, itaconic acid, chrotonic acid and maleic acid anhydride. Examples of (meth)acrylamide derivatives include, but are not limited to (meth)acrylamide (including N-substituted products).

Examples maleimide derivatives include but are not limited to maleicacid imide (including N-substitution products).

The shell polymer can comprise at least 5, at least 10, at least 15 or at least 20% up to 70, up to 60, or up to 50% by weight based on total weight of the particle.

The weight ratio of the core layer to the shell layer of a preferred rubber particle can be in the range of from at least 30:70, at least 40:60, or at least 50:50 up to 95:5, up to 90:10, up to 85:15, or up to 80:20.

The shell can have a Tg of at least 50, at least 70, or at least 100° C.

The core/shell polymer particles can be produced by a well-known method, for example, emulsion polymerization, suspension polymerization, or micro-suspension polymerization. Among them, a production process by the emulsion polymerization is suitable from the view point that it is easy to design composition of the core/shell polymer particles, and it is easy to produce the particles at an industrial scale and maintain quality of the rubbery polymer particles suitable to the process of this invention. As the emulsifying or dispersing agent in an aqueous medium, it is preferred to use those that maintain emulsifying or dispersion stability even in the case where pH of the aqueous latex is neutral. Specifically, they include, for example, nonionic emulsifier or dispersant such as alkali metal salts or ammonium salts of various acids, for example, alkyl or aryl sulfonic acids typically represented by dioctyl sulfosuccinic acid or dodecylbenzene sulfonic acid, alkyl or aryl sulfonic acid typically represented by dodecyl sulfonic acid, alkyl or aryl ether sulfonic acid, alkyl or aryl substituted phosphoric acid, alkyl or aryl ether substituted phosphoric acid, or N-alkyl or aryl sarcosinic acid typically represented by dodecyl sarcosinic acid, alkyl or aryl carboxylic acid typically represented by oleic acid or stearic acid, alkyl or aryl ether carboxylic acids, and alkyl or aryl substituted polyethylene glycol, and dispersant such as polyvinyl alcohol, alkyl substituted cellulose, polyvinyl pyrrolidone or polyacrylic acid derivative. They may be used alone or in combination of two or more.

The particle can have an alkylacrylate copolymer core surrounded by a methyl methacrylate copolymer shell. The particle can have a core with a T_(g) of less than 0° C. and the shell has a Tg of at least 100° C. According to Commercially available particles that are suitable include Paraloid™ EXL 5136 from The Dow Chemical Company.

The optical modifier can comprise more than one (e.g. 2 or 3) types of polymeric particle as described above.

Compatibilizer

The compatibilizer is a polymer characterized in that it has similar chemical structure to the base polymer and has pendant and/or end groups that have an affinity to the core/shell polymer particle. Thus, where the base polymer is a polyolefin, the compatibilizer can be the same class of polyolefin (e.g. if the base polymer is a polyethylene the compatibilizer advantageously can be a polyethylene functionalized with a group having affinity to the shell material). The compatibilizer can be a polyolefin/acrylate copolymer (e.g. polyethylene/acrylate such as ELVALOY AC™ from DuPont) or a polyolefin/acrylic acid copolymer (e.g. polyethylene/acrylic acid such as NUCREL™ from DuPont), or a polyolefin/carboxylic acid copolymer of a polyolefin/maleic anhydride ester copolymer. A polyolefin based compatibilizer can be grafted with one or more anhydride groups or acrylate groups or acrylic acid groups. For example, if the base polymer comprises LLDPE as its sole or major component, the compatibilizer can be a polyethylene such as an LDPE or HDPE grafted with an anhydride group such as maleic anhydride. One example is Fusabond™ E265 from The Dow Chemical Company. The amount of compatibilizer can be from 0.5 or from 1 weight percent up to 30, up to 20, up to 15, or up to 10 weight percent based on total weight of the filament. The amount of the compatibilizer may increase as the amount of acrylic polymer particle increases. The compatibilizer can be a mixture of polymers as described above as compatibilizers.

Colorant and Other Additives

The filament according can comprise a colorant. The colorant will generally be a pigment. The pigment may be provided neat or in a polymeric carrier or matrix material. The amount of colorant is from 0, from 0.5, or from 1 up to 10 or up to 5 weight percent based on total weight of the filament. The pigment may be provided in a carrier polymer such as polyethylene or polypropylene.

Optionally, the filaments may further include one or more additives. Non-limiting examples of suitable additives include IR reflectants, antioxidants, UV stabilizers, UV absorbers, fire retardants, luminescent compounds, processing aids (such as fluoropolymers or fluoroelastomers including Dynamar™ from 3M), fillers, antistatic agents, nucleating agents, slip agents, plasticizers, lubricants, viscosity control agents, tackifiers, anti-blocking agents, surfactants, extender oils, acid scavengers, and metal deactivators. If an optional additive is used it can be present in amounts less than 5, less than 4, less than 3, less than 2, or less than 1% by weight and the total amount of all the additives is less than 10, less than 8 , less than 6, less than 4 or less than 2% by weight. They may be used in amount of at least 0.001, at least 0.01, or at least 0.1% by weight.

Filament Structure

The turf filaments can be monocomponent fibers where the above composition forms the entire fiber. Alternatively, the filaments could be bi-component fibers. For example, the bicomponent fibers could have a core/sheath architecture wherein the above composition forms the sheath of the fiber. The core of the fiber could be other polymers such as other polyolefins, such as polypropylene or other polyethylenes (e.g., such as LDPE) polyesters, such as PET, or polyamides.

The filaments can be made by normal fiber manufacturing methods such as for example, melt spinning and/or slit film extrusion. These processes may include stretching the extruded or spun filaments. Stretching may be in amounts of at least 1 or 2 or 3 or 4 times the original length up to 6 times the original length. Spin or extrusion temperatures may be in the range of at least 150 or 170 or 190° C. to 270 or 250° C. The processing may include annealing the filaments after stretching.

Unless stated to the contrary, implicit from the context, or customary in the art, all parts and percents are based on weight, all temperatures are in ° C., and all test methods are current as of the filing date of this disclosure.

The term “composition,” as used herein, refers to a mixture of materials which comprises the composition, as well as reaction products and decomposition products formed from the materials of the composition.

“Polymer” means a polymeric compound prepared by polymerizing monomers, whether of the same or a different type. The generic term polymer thus embraces the term homopolymer (employed to refer to polymers prepared from only one type of monomer, with the understanding that trace amounts of impurities can be incorporated into the polymer structure), and the term interpolymer as defined hereinafter. Trace amounts of impurities (for example, catalyst residues) may be incorporated into and/or within the polymer. A polymer may be a single polymer, a polymer blend or a polymer mixture, including mixtures of polymers that are formed in situ during polymerization.

The term “interpolymer,” as used herein, refers to polymers prepared by the polymerization of at least two different types of monomers. The generic term interpolymer thus includes copolymers (employed to refer to polymers prepared from two different types of monomers), and polymers prepared from more than two different types of monomers.

The terms “olefin-based polymer” or “polyolefin”, as used herein, refer to a polymer that comprises, in polymerized form, a majority amount of olefin monomer, for example ethylene or propylene (based on the weight of the polymer), and optionally may comprise one or more comonomers.

The term, “ethylene/α-olefin interpolymer,” as used herein, refers to an interpolymer that comprises, in polymerized form, a majority amount (>50 mol %) of units derived from ethylene monomer, and the remaining units derived from one or more α-olefins. Typical α-olefins used in forming ethylene/α-olefin interpolymers are C₃-C₁₀ alkenes.

The term, “ethylene/α-olefin copolymer,” or “ethyelen/alpha-olefin” as used herein, refers to a copolymer that comprises, in polymerized form, a majority amount (>50 mol %) of ethylene monomer, and an α-olefin, as the only two monomer types.

The term “α-olefin”, as used herein, refers to an alkene having a double bond at the primary or alpha (α) position.

The terms “comprising,” “including,” “having,” and their derivatives, are not intended to exclude the presence of any additional component, step or procedure, whether or not the same is specifically disclosed. In order to avoid any doubt, all compositions claimed through use of the term “comprising” may include any additional additive, adjuvant, or compound, whether polymeric or otherwise, unless stated to the contrary. In contrast, the term, “consisting essentially of” excludes from the scope of any succeeding recitation any other component, step or procedure, excepting those that are not essential to operability. The term “consisting of” excludes any component, step or procedure not specifically delineated or listed. The compositions discussed herein as comprising can be compositions consisting essentially of or consisting of the components listed.

“Polyethylene” or “ethylene-based polymer” shall mean polymers comprising a majority amount (>50 mol %) of units which have been derived from ethylene monomer. This includes polyethylene homopolymers or copolymers (meaning units derived from two or more comonomers). Common forms of polyethylene known in the art include Low Density Polyethylene (LDPE); Linear Low Density Polyethylene (LLDPE); Ultra Low Density Polyethylene (ULDPE); Very Low Density Polyethylene (VLDPE); single-site catalyzed Linear Low Density Polyethylene, including both linear and substantially linear low density resins (m-LLDPE); Medium Density Polyethylene (MDPE); and High Density Polyethylene (HDPE). These polyethylene materials are generally known in the art; however, the following descriptions may be helpful in understanding the differences between some of these different polyethylene resins.

The term “LDPE” may also be referred to as “high pressure ethylene polymer” or “highly branched polyethylene” and is defined to mean that the polymer is partly or entirely homo-polymerized or copolymerized in autoclave or tubular reactors at pressures above 14,500 psi (100 MPa) with the use of free-radical initiators, such as peroxides (see for example U.S. Pat. No. 4,599,392, which is hereby incorporated by reference). LDPE resins typically have a density in the range of 0.916 to 0.935 g/cm³.

The term “LLDPE”, includes both resin made using the traditional Ziegler-Natta catalyst systems and chromium-based catalyst systems as well as single-site catalysts, including, but not limited to, bis-metallocene catalysts (sometimes referred to as “m-LLDPE”) and constrained geometry catalysts, and includes linear, substantially linear or heterogeneous polyethylene copolymers or homopolymers. LLDPEs contain less long chain branching than LDPEs and includes the substantially linear ethylene polymers which are further defined in U.S. Pat. Nos. 5,272,236, 5,278,272, 5,582,923 and 5,733,155; the homogeneously branched linear ethylene polymer compositions such as those in U.S. Pat. No. 3,645,992; the heterogeneously branched ethylene polymers such as those prepared according to the process disclosed in U.S. Pat. No. 4,076,698; and/or blends thereof (such as those disclosed in U.S. Pat. Nos 3,914,342 or 5,854,045). The LLDPEs can be made via gas-phase, solution-phase or slurry polymerization or any combination thereof, using any type of reactor or reactor configuration known in the art.

The term “HDPE” refers to polyethylenes having densities greater than about 0.935 g/cm³ and up to about 0.970 g/cm³, which are generally prepared with Ziegler-Natta catalysts, chrome catalysts or single-site catalysts including, but not limited to, bis-metallocene catalysts and constrained geometry catalysts.

“Blend”, “polymer blend” and like terms mean a composition of two or more polymers. Such a blend may or may not be miscible. Such a blend may or may not be phase separated. Such a blend may or may not contain one or more domain configurations, as determined from transmission electron spectroscopy, light scattering, x-ray scattering, and any other method known in the art. Blends are not laminates, but one or more layers of a laminate may contain a blend. Such blends can be prepared as dry blends, formed in situ (e.g., in a reactor), melt blends, or using other techniques known to those of skill in the art.

“Polypropylene” means polymers comprising greater than 50% by weight of units which have been derived from propylene monomer. This includes polypropylene homopolymers or copolymers (meaning units derived from two or more comonomers). Common forms of polypropylene known in the art include homopolymer polypropylene (hPP), random copolymer polypropylene (rcPP), impact copolymer polypropylene (hPP+at least one elastomeric impact modifier) (ICPP) or high impact polypropylene (HIPP), high melt strength polypropylene (HMS-PP), isotactic polypropylene (iPP), syndiotactic polypropylene (sPP), and combinations thereof.

For ranges, stated upper and lower limits can be combined to form ranges (e.g. “at least 1 or at least 2 weight percent” and “up to 10 or 5 weight percent” can be combined as the ranges “1 to 10 weight percent”, or “1 to 5 weight percent” or “2 to 10 weight percent” or “2 to 5 weight percent”). The terms “a” and “an” and “the” do not denote a limitation of quantity and are to be construed to cover both the singular and the plural, unless otherwise indicated herein or clearly contradicted by context.

This disclosure further encompasses the following aspects.

Aspect 1. A turf filament comprising from 50 to 99.5 weight percent of a base polymer selected from polyolefins, polyamides, polyesters and combinations thereof, from 0.1 to 20 weight percent of polymer particles having a core and a shell structure where the core comprises a first polymeric material having a first refractive index and the shell comprises a second polymeric material having a second refractive index that is different from the first refractive index, from 0.5 to 30 weight percent of a compatibilizer and from 0 to 10 weight percent of a colorant based on total weight of the filaments.

Aspect 2. The filament of claim 1 wherein the base polymer comprises a linear low density polyethylene.

Aspect 3. The filament of aspect 1 or 2 wherein the first polymeric material of the core of the polymer particle is elastomeric and the second polymeric material of the shell of the polymer particle is a thermoplastic.

Aspect 4. The filament of any one of the preceding aspects wherein the shell comprises an acrylic polymer.

Aspect 5. The filament of any one of the preceding aspects wherein the compatibilizer is a polyolefin copolymer with acrylic acid functionality, a polyolefin copolymer with an acrylate functionality, a polyolefin copolymer with a maleic anhydride ester functionality or is a polyolefin grafted with one or more anhydride group, acrylate group or carboxylic acid group.

Aspect 6. The filament of any one of the preceding aspects wherein the particles have an average size in the range of 1 to 10 microns.

Aspect 7. The filament of any one of the preceding aspects having 0.5 to 10 weight percent of the particles, 0.5 to 10 weight percent of the compatibilizer and 0.5 to 10 weight percent of the colorant based on total weight of the filament.

Aspect 8. The filament of any one of the preceding aspects further comprising one or more of infrared reflectants, UV stabilizers, anti-oxidants, fire-retardants luminescent compounds, processing aids, and fillers.

Aspect 9. The filament of any of the preceding aspects wherein the first and second refractive index differ by at least 0.02.

Aspect 10. The filament of any of the preceding aspects comprising

-   -   50 to 99.5, preferably 80 to 98 weight percent of polyolefin,         preferably the polyolefin comprises linear low density         polyethylene,     -   0.1 to 20, preferably 0.5 to 10, more preferably 1 to 7 weight         percent of a core shell polymeric particle having an elastomeric         core and an acrylic polymer shell, preferably having a particle         size of 1 to 10 microns,     -   0.5 to 30, preferably 0.5 to 15 weight percent a compatibilizer         comprising a polyolefin having carboxylic acid, acrylate         functionality, or maleic anhydride functionality, preferably         maleic anhydride functionality     -   0 to 10, preferably 0 to 5, more preferably 0.5 to 5 weight         percent of a colorant.

Aspect 11. A synthetic turf comprising a substrate having a plurality of the turf filaments of any one of the preceding claims extending from the substrate.

Aspect 12. The synthetic turf of claim 11 further comprising infill particles on the substrate and around the filaments.

Aspect 13. The synthetic turf of claim 11 or 12 further comprising a backing sheet to hold the filaments in place.

EXAMPLES Formulating the Composition

Materials used:

-   -   DOWLEX™ 2107GC LLDPE resin, Density=0.917 g/cm3, melt index=2.3         g/10 min (190° C., 2.16 kg).     -   PARALOID™ EXL-5136 core/shell polymer in powder form.     -   FUSABOND™ E265 as compatibilizer. This component is a HDPE         grafted with maleic anhydride. Density is 0.950 g/cm3 and melt         index=12 g/10 min (190° C., 2.16 kg).     -   Sicolen green 85-125345, from BASF, was used as color         masterbatch.

The materials were combined according to the and melt blended on a Buss Kneader Compounder as 120 rpm kneader speed and extruded at 8 kg/hr at temperature profile of 110/130/140/120/125° C. The following table 1 summarizes the formulations of the different films, together with the fabrication conditions. All blends were melt-blended prior to extrusion on a Buss Kneader Compounder at 120 rpm (kneader speed), 3 A (motor current), 8 kg/h, 60 rpm (screw speed) and a 110/130/140/120/125° C. temperature profile. The formulation as set forth in Table were extruded according to the conditions set out in Table 1.

TABLE 1 Sample formulations and processing conditions Description (% listed are weight percent based on total weight Thickness, Output, Die gap Take-off Motor Melt P, Melt T, ID of composition) microns kg/h mm m/min A bar ° C. rpm Comp. DOWLEX 2107GC 200 8 0.8 3 5.6 201 222 88 Ex 1 Comp. DOWLEX 2107GC + 1% 200 8 0.8 3 5.4 198 224 88 Ex. 3 PARALOID 5136 Ex 1 DOWLEX 2107GC + 1% 200 8 0.8 3 5.4 199 223 88 PARALOID 5136 + 0.5% FUSABOND E265 Ex. 2 DOWLEX 2107GC + 5% 200 8 0.8 3 5.5 202 224 88 PARALOID 5136 + 2.5% FUSABOND E265 Ex. 3 DOWLEX 2107GC + 1% 200 8 0.8 3 5.6 200 224 88 PARALOID 5136 + 2% FUSABOND E265 Ex. 4 DOWLEX 2107GC + 5% 200 8 0.8 3 5.5 200 223 88 PARALOID 5136 + 10% FUSABOND E265 Comp. DOWLEX 2107GC + 5% 200 8 0.8 3 5.3 196 224 88 Ex. 2 Sicolen green 85- 125345 Ex. 5 DOWLEX 2107GC + 1% 200 8 0.8 3 5.3 194 224 88 PARALOID 5136 + 0.5% FUSABOND E265 + 5% Sicolen green 85- 125345 Ex 6 DOWLEX 2107GC + 5% 200 8 0.8 3 5.3 198 223 88 PARALOID 5136 + 2.5% FUSABOND E265 + 5% Sicolen green 85- 125345

Gloss 45 degrees was measured according to ASTM D2457 and Haze was evaluated according to ASTM D1003. Mechanical properties of the films were also evaluated through tear strength measurements (ASTM D1922), which can correlate with the durability in the final turf application. The results are shown in Table 2.

TABLE 2 Gloss MD CD Sample 45 Tear Tear ID deg Haze % (g) (g) Gels/m² Comp 84 7.5 4144 4103 — Ex 1 Ex 1 62 35.1 4218 4225 5091 Ex 2 34 80.6 4125 4203 — Ex 3 61 31.7 4089 4237 3665 Ex 4 30 78.2 3634 3862 — Comp. 50 — 4337 4392 — Ex 2 Ex. 5 46 — 4425 4485 — Ex. 6 29 — 4459 4551 — Comp. — — — — 26417  Ex 3

Adding 1% of optical modifier (Ex.1, Ex 3) led to a reduction of gloss of about 27% and an increase of haze of about 340%. Increasing the concentration of optical modifier to 5% (Ex. 2, Ex. 4) resulted in further improvement, with a reduction of 62% in gloss and an increase of 950% in haze. In formulations with colorant, adding the Paraloid™ material also resulted in gloss reduction.

The effect of the optical modifier on mechanical properties was evaluated with the tear strength test in the machine direction (MD) and the cross direction (CD). The inclusion of the Paraloid™ particles with the compatibilizer shows no significant effect on tear strength as compared to the LLDPE with and without colorant but without the other additives.

The films of Ex. 1, Ex 3 and comparative ex. 3 (no compatibilizer) were evaluated for the number of gels observed by visual inspection using a camera indicating the number of defects per square meter. Without the compatibilizer, a composition with the Paraloid™ particles show a high number of gels or defects. This could lead to yarn breakage during stretching and/or use. 

1. A turf filament comprising from 50 to 99.5 weight percent of a base polymer selected from polyolefins, polyamides, polyesters and combinations thereof, from 0.1 to 20 weight percent of polymer particles having a core and a shell structure where the core comprises a first polymeric material having a first refractive index and the shell comprises a second polymeric material having a second refractive index that is different from the first refractive index, from 0.5 to 30 weight percent of a compatibilizer and from 0 to 10 weight percent of a colorant based on total weight of the filaments.
 2. The filament of claim 1 wherein the base polymer comprises a linear low density polyethylene.
 3. The filament of claim 1 wherein the first polymeric material of the core of the polymer particle is elastomeric and the second polymeric material of the shell of the polymer particle is a thermoplastic.
 4. The filament of claim 3 wherein the shell comprises an acrylic polymer.
 5. The filament of claim 1, wherein the compatibilizer is a polyolefin copolymer with acrylic acid, a polyolefin copolymer with an acrylate, a polyolefin copolymer with a maleic anhydride ester or is grafted with one or more anhydride group, acrylate group or carboxylic acid group.
 6. The filament of claim 1 wherein the particles have an average size in the range of 1 to 10 microns.
 7. The filament of claim 1 having 0.5 to 10 weight percent of the particles, 0.5 to 10 weight percent of the compatibilizer and 0.5 to 10 weight percent of the colorant based on total weight of the filament.
 8. The filament of claim 1 further comprising one or more of infrared reflectants, UV stabilizers, anti-oxidants, fire-retardants luminescent compounds, processing aids, and fillers.
 9. The filament of claim 1 wherein the first and second refractive index differ by at least 0.02.
 10. A turf filament comprising 50 to 99 weight percent of a polyolefin 0.1 to 20 weight percent of a core shell polymeric particle having an elastomeric core and an acrylic polymer shell and, 0.5 to 30 weight percent of a compatibilizer comprising a polyolefin having carboxylic acid, acrylate functionality, or maleic anhydride functionality 0 to 10 weight percent of a colorant.
 11. A synthetic turf comprising a substrate having a plurality of turf filaments of extending from the substrate wherein the turf filaments comprise 50 to 99.5 weight percent of a base polymer, 0.1 to 20 weight percent of polymeric particles comprising a core and a shell, 0.5 to 30 weight percent of a compatibilizer and 0 to 10 weight percent of a colorant based on total weight of the filaments, and wherein the polymeric particles are characterized in that (a) the core comprises a first polymeric material having a first refractive index and the shell comprises a second polymeric material having a second refractive index that is different front the first refractive index, and/or (b) the core is elastomeric and the shell comprises an acrylic polymer.
 12. The synthetic turf of claim 11 further comprising infill particles on the substrate and around the filaments.
 13. The synthetic turf of claim 11 further comprising a backing sheet to hold the filaments in place.
 14. The filament of claim 3 wherein the polymer particles include an intermediate layer on the core and the shell layer is graft polymerized on the core or on the intermediate layer.
 15. The synthetic turf of claim 11 wherein the base polymer is a polyethylene.
 16. The synthetic turf of claim 11 wherein the polymer particles have a particle size of 1 to 10 microns.
 17. The synthetic turf of claim 11 wherein the compatibilizer comprises polyolefin copolymer with acrylic acid, a polyolefin copolymer with an acrylate, a polyolefin copolymer with a maleic anhydride ester or is grafted with one or more anhydride group, acrylate group or carboxylic acid group. 